The present invention relates to a method and a device for establishing an optical connection between at least one optoelectronic component in a first substrate, which emits or receives optical radiation almost perpendicular to a substrate surface of the first substrate, and at least one optical waveguide, in particular an optical fiber, aligned with one first end almost parallel to the substrate surface.
Optical connection technology, as presently employed in long distance connections or in local area networks (LANs), is not optimally suited for signal connections inside computer systems. The hitherto available plug-type connections between the optical transmitters or receivers and the utilized optical waveguides, in particular optical fibers, are, on the one hand, too expensive for such type use, and on the other hand take up too much space.
Especially in the use of surface-emitting semiconductor lasers, so-called VCSELs (vertical cavity surface emitting laser), there is a need for space-saving, cost-effective methods and devices to connect these lasers to optical waveguides, in particular multimode glass fibers which are aligned with one end almost parallel to the surface of the semiconductor substrate in which the semiconductor laser is integrated. The beam deflection required for this purpose is usually realized by using glass fibers, whose ends are cut at an angle of 45° and polished. The fiber is then positioned exactly over the semiconductor laser by means of micropositioning in such a manner that the laser beam emitted into the glass fiber by the semiconductor can be deflected 90° by means of reflection at the polished end surface. The polishing process, however, is relatively complicated and time consuming. Furthermore, each single fiber has to be individually micropositioned and fixed over the respective semiconductor laser. These steps make the connecting process very expensive in production.
U.S. Pat. No. 6,389,202 B1 describes a method and a device for optical coupling of optoelectronic components with optical fibers, in which the time and effort involved in positioning is reduced. For this purpose, a defined trough is placed in a carrier substrate by means of plasma ion etching to guide the fiber. In this case, too, beam deflection occurs by slanting the end surface of the fiber at an angle of 45°. The semiconductor substrate with the optoelectronic component is then placed on the carrier substrate.
U.S. Pat. No. 5,168,537 describes a device for optical connection between a multiplicity of light conducting fibers and optoelectronic elements, in which one or a multiplicity of prisms is/are disposed inside a plug housing for the fiber ends for beam deflection. However, there is no information provided in this printed publication about the production of the device, in particular, about how the prisms are built in.
U.S. Pat. No. 5,764,832 A describes another technology for establishing an optical connection between an integrated optoelectronic semiconductor element and an optic fiber. In this technology, a trough, which serves to receive and guide the fiber, is etched into a silicon substrate in an anisotropic etching step. Due to the orientation of the crystal planes of the silicon, this etching step produces an end surface with a gradient of approximately 54°, which acts as a reflection surface for deflecting the optical beam into an optoelectronic semiconductor component or from an optoelectronic semiconductor, which is placed on the substrate. However, due to the crystal structure of the silicon and the angle of the end surface related thereto, this technology does not permit 90° deflection.